This invention relates to a video conference system connecting at least two groups of remote conferees divided in sub-groups each containing a small number of conferees and provided with an individual videotelephone and more particularly a video conference system utilizing voice controlled switching to automatically direct the field of view of the camera of a particular videotelephone toward the image receivers of the other videotelephones.
Video conference systems utilizing voice controlled switching are known in the prior art. U.S. Pat. No. 3,601,530 issued Aug. 24, 1971 disclosed a system in which at at least two locations, a plurality of video cameras are used and the field of each is restricted to a relatively small number of people who can be seen well enough to provide good visual contact. Voice voting and switching are used to determine the location of the person in the group who is talking and in response thereto, the appropriate camera is enabled so that the talker will be seen at the remote location. To this end, a plurality of microphones, equal in number to the videotelephones are positioned before a group and these microphones are respectively associated with the videotelephones. The address of the person who is speaking is determined by the level of speech signals generated in each of the microphones. In response to the loudest speech signal, a comparison circuit causes the camera of the videotelephone associated with the microphone generating the loudest speech signal to be enabled. It is the video image of this camera that is transmitted to the remote location along with the audio signal. As different people in the group speak, in turn, the appropriate cameras covering the same are successively enabled so that the outgoing video provides a good visual image of the person when talking. A corresponding operation takes place at the other location, i.e., the video conferencing is two-way.
In this prior art conference system, a conferee in the local conference room or station sees on his assigned image receiver the incoming video image sent by the camera assigned to a talker located in a remote conference room. He also sees the outgoing video sent from the local station to the remote one on a centrally disposed image receiver. But the viewer does not see on his assigned image receiver the talker when the viewer and talker are in the same conference room.
The primary object of the present invention is to establish a visual telephone conference network in which all the videotelephones of the network are treated identically irrespective of the conference room in which they are located.
A related object of the invention is to provide a voice controlled visual telephone conference network with two voice voting stages : a talker group voice voting stage and a talker voice voting stage.